I'd have to say Inuyasha. It did have a great ending don't get me wrong! BUT they left you with so many questions like was miroku's curse ever broken? Did naraku ever get deated? If so by whom? stuff like that.

Now I love inuyasha it really is a great show I mean nothing bad to disrespect it but that's just how I see the end.

i feel the same way about Inuyasha as you do.
Tsubasa Reservoir Chronicle-IT FUCKING SUCKED!they didn't even end thet're journey or anything!.....nothing was really explained.....like with Syaoran's past and the the other syaoran in the pod of water thingy.....or why Fai had to run away from Ashura....it did show Kurogane's past though....it was a lot like how Inuyasha ended!....also it left u with a lot of answered ?'s like who was that other syaoran? who i syaoran really? do they ever get all of sakura's feathers back? if so will she ever be able to remember syaoran? will kurogane get home? will fai ever stop runing? and who really is fai? and studd lke that.
Loveless-this was also a disappointment....i mean it gets all weird with some shit and then it ends.....it also didn't really explain anything....like who seimei's murderer was or the about the organization....but to put it simply the ending sucked.
Full Moon wo Sagashite-it was good but the manga ending was way better!....in the anime it kinda showed that mitsuki got takuto back but never showed that eichi-kun reached out of the sky and said her name and was kinda there as a ghost an the he disappeared....and in the manga it really shows that takuto found mitsuki and she started singing with her own name an they got back together.....so this was kind of a disappointment the ending could have been better but at least it got an ending that was half decent.
Shaman King-this one was a bit of a disappointment.....it didn't show if yoh got to be shaman king or not....but this one to at least got somewhat of an ending.
Sukisho, card captor sakura, d.n angel, and gravitation